1. Technical Field
Embodiments of the present invention generally relate to methods of fabricating semiconductor devices, and more particularly, to a method of fabricating a semiconductor device wherein fine contact holes are formed using a mask pattern formed using molding patterns.
2. Discussion of the Related Art
A semiconductor device includes discrete devices such as transistors, resistors and capacitors. The discrete devices are electrically connected to one another through contact plugs or interconnections, formed in contact holes passing through an insulating layer. For example, a NAND-type flash memory device may include word lines crossing above active regions spaced apart from one another inside a semiconductor substrate, and a selection line adjacent to the word lines and crossing above the active regions. The NAND-type flash memory device may also include bit lines insulated from the word and selection lines by an interlayer dielectric layer and crossing above them. The bit lines may be electrically connected to the active regions adjacent to the select line through the contact holes, respectively. The contact holes may be generally formed through a patterning process. The patterning process includes forming a mask pattern having hole-shaped openings on the interlayer dielectric layer through a photo-process and etching the interlayer dielectric layer exposed through the openings.
Because the size of the contact holes becomes smaller as the integration density of the semiconductor device increases, the size of the openings should be reduced. However, it is difficult to control the photo-process as it is required to reduce the size of the openings. For example, as the topology on the semiconductor substrate is complicated, diffuse reflections may be generated due to patterns, such as the selection and word lines, during the photo-process. Therefore, there is a limit in ensuring the uniform size of each of the openings. As a result, a uniform resistance is not secured in a contact plug filling each of the contact holes. Therefore, the reliability of a semiconductor device is degraded.